Lighting Control System with Emergency Mode

ABSTRACT

A load control system has a system controller and a plurality of load control devices which receive power from a utility power source. The load control system also includes at least one emergency load control device which receives power from a backup power source in the event of a power failure of the utility power source. The emergency load control device is configured to enter an emergency mode during the power failure of the utility power source, wherein in the emergency mode, the emergency load control device controls respective electrical loads according to emergency mode preset settings, and the emergency load control device transmits a message to the system controller to indicate the emergency load control device is in the emergency mode. The system controller is configured to transmit a message to the emergency load control device to exit the emergency mode when power from the utility power source is restored.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/907,419, filed Jun. 22, 2020; which is a continuation of U.S. patentapplication Ser. No. 16/278,475, filed Feb. 18, 2019, now U.S. Pat. No.10,694,612 issued Jun. 23, 2021; which claims the benefit of U.S.Provisional Patent Application No. 62/631,696, filed Feb. 17, 2018, thedisclosures of which are hereby incorporated by reference herein in itsentirety.

BACKGROUND

A user environment, such as a residence or an office building forexample, may be configured using various types of load control systems.A lighting control system may be used to control the lighting loads inthe user environment. A motorized window treatment control system may beused to control the natural light provided to the user environment. Aheating, ventilation, and air-conditioning (HVAC) system may be used tocontrol the temperature in the user environment.

Each load control system may include various control devices, includinginput devices and load control devices. The load control devices mayreceive digital messages, which may include load control instructions,for controlling an electrical load from one or more of the inputdevices. The load control devices may be capable of directly controllingan electrical load. The input devices may be capable of indirectlycontrolling the electrical load via the load control device. The loadcontrol devices may be emergency load control devices and may controlone or more loads to an emergency mode when a loss of utility power hasoccurred.

Automatic load control relays (ALCR) may be used to provide power to oneor more lighting loads when utility power has been lost. However, ALCRsmay add cost and complexity to a lighting control system, requiringadditional wiring and increased time to install. Therefore, it isdesirable for a load control system to have an emergency mode withminimal additional wiring, which may not require the use of ALCRs.

SUMMARY

Described herein is an example load control system wiring for emergencydevices. According to a first example, an emergency load control devicemay startup in an emergency mode powered from a backup power source whena power outage of a utility power source has occurred. In the emergencymode, the emergency load control device may control its respectivelighting load to one or more emergency preset light levels and/or colortemperature. The emergency lighting load may periodically transmit amessage to one or more system controllers indicating that the emergencylighting load is in the emergency mode. The emergency lighting load mayremain in the emergency mode until receiving a message from the systemcontroller to exit the emergency mode.

According to a second example described herein, a power detector may bewired to the utility power to determine when a power outage of theutility power source occurs. Based on detecting that a power outage hasoccurred, the power detector may transmit a message to one or moresystem controllers which may transmit a command to tell the emergencyload control devices to enter emergency mode.

According to a third herein, a load control system with multi-phasepower may have one or more power detectors on one or more phases ofpower. The emergency load control devices may be configured to enteremergency mode upon detecting a power blip (i.e., when starting up aftera power on reset). In the emergency mode, the emergency load controldevices may transmit one or more messages indicating the emergency loadcontrol device is in the emergency mode. The system controller mayreceive the one or more messages and may further detect when power hasbeen restored on the respective phases of power. The system controllermay further transmit a message to communicate to the emergency loadcontrol devices to exit the emergency mode when power is restored on therespective phase of power.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an example load control system according to a first example.

FIG. 2 is an example process which may be executed by a control deviceto enter and exit an emergency mode.

FIG. 3 is an example process which may be executed by a systemcontroller, for example, to instruct one or more control devices to exitan emergency mode.

FIG. 4 is an example load control system according to a second example.

FIG. 5 is an example load control system according to a third example.

FIG. 6 is an example process which may be executed by a systemcontroller during a power outage.

FIG. 7 is an example block diagram of a control device.

FIG. 8 is an example block diagram of a system controller.

DETAILED DESCRIPTION

FIG. 1 is an example load control system 100 showing power provided toone or more devices in a space. The load control system 100 may containone or more control-target devices, for example, load control devices120, 122, 124. The load control devices may be configured to controlelectrical loads. For example, the load control devices 120, 122, 124may be configured to control electrical lighting loads 130, 132, 134,respectively as shown. The electrical lighting loads 130, 132, 134 maybe fluorescent, light-emitting diode (LED), halogen, incandescent, orsodium-vapor lamps, or any other type of lighting load, for example.Each load control device 120, 122, 124 may be configured to directlycontrolling the amount of power provided to an electrical load, forexample, lighting loads 130, 132, 134, and may be controlled by acontrol-source device, such as a remote control or wall switch, etc.(not shown).

Control devices (e.g., a control-source device and/or a control-targetdevice) may communicate with each other and/or other devices via a wiredand/or a wireless communication link. For example, the control devicesmay communicate via radio frequency (RF) signals 172. The RF signals 172may be transmitted via any known RF communication technology and/orprotocol (e.g., near field communication (NFC); BLUETOOTH®; WI-FI®;ZIGBEE®; a proprietary communication channel, such as CLEAR CONNECT™;etc.). A control device may be both a control-target and acontrol-source device.

A control-source device may be an input device that indirectly controlsthe amount of power provided to an electrical load by transmittingmessages, for example, digital messages, to the control-target device.The messages may include control instructions (e.g., load controlinstructions) or another indication that causes the control-targetdevice to determine load control instructions for controlling anelectrical load. Example control-source devices may include remotecontrol devices (not shown), an occupancy sensor 112, a daylight sensor,a window sensor, etc. The control-source devices may include a wired orwireless device. The control-source devices may include a controldevice, such as a dimmer switch, an electronic switch, or the like.

The load control system 100 may include a system controller 140 (e.g., ahub device) configured to transmit and/or receive messages via wiredand/or wireless communications. For example, the system controller 140may be configured to transmit and/or receive the RF signals 172, tocommunicate with one or more control devices (e.g., control-sourcedevices and/or control-target devices). The system controller 140 maycommunicate messages between associated control devices, for example.One or more control devices may be associated to each other and/or tothe system controller 140 during a configuration of the load controlsystem, wherein associated devices may be configured to communicatemessages to each other. The system controller 140 may be coupled to oneor more wired control devices (e.g., control-source devices and/orcontrol-target devices) via a wired communication link. For example, thesystem controller 140 may be on-site at the load control environment100, or the system controller 140 may be located at a remote locationfrom the load controls devices 120, 122, 124, i.e., in a different roomof a building, etc. Though the system controller 140 is shown as asingle device, the load control system 100 may include multiple systemcontrollers and/or the functionality thereof may be distributed acrossmultiple devices.

The occupancy sensor 112 may be configured to detect occupancy and/orvacancy conditions in an area in which the load control system 100 isinstalled. The occupancy sensor 112 may transmit messages tocontrol-target devices via the RF communication signals 172 in responseto detecting the occupancy or vacancy conditions. The occupancy sensor112 may operate as a vacancy sensor, such that messages are transmittedin response to detecting a vacancy condition (e.g., messages may not betransmitted in response to detecting an occupancy condition). Examplesof RF load control systems having occupancy and/or vacancy sensors aredescribed in greater detail in U.S. Pat. No. 8,009,042, issued Aug. 10,2011, entitled RADIO-FREQUENCY LIGHTING CONTROL SYSTEM WITH OCCUPANCYSENSING; U.S. Pat. No. 8,199,010, issued Jun. 12, 2012, entitled METHODAND APPARATUS FOR CONFIGURING A WIRELESS SENSOR; and U.S. Pat. No.8,228,184, issued Jul. 24, 2012, entitled BATTERY-POWERED OCCUPANCYSENSOR, the entire disclosures of which are hereby incorporated byreference.

The load control devices 120, 122, 124 may control the respectivelighting loads 130, 132, 134 in response to a command from acontrol-source device, such as the occupancy sensor 172, and/or thesystem controller 140. For example, the load control devices 120, 122,and/or 124 may be configured to turn their respective lighting loadsfrom an off state to an on state in response to receiving a message fromthe occupancy sensor 112 indicating that the area is occupied. Examplesof load control systems with control-source and control-target devicesresponsive to a system controller are described in more detail in U.S.Pat. No. 6,803,728, issued Oct. 12, 2004, entitled “System For ControlOf Devices,” and U.S. Pat. No. 9,553,451, issued Jan. 24, 2017, entitled“Load Control System Having Independently-Controlled Units Responsive ToA Broadcast Controller,” the entire disclosures of which areincorporated herein by reference.

The load control devices 120, 122, 124 may be wall-mounted load controldevices, such as switches or dimmers. Additionally or alternatively, theload control devices may be installed above the ceiling or integratedinto a lighting fixture. For example, the load control devices may be adimming or switching module, such as a power pack; a light emittingdiode (LED) driver; a fluorescent ballast, etc. The control devices120-124 may be configured to control power to the one or more lightingloads 130-134. The control devices 120-124 may have power failurememory, i.e., may periodically store a current state of the lightingload 130-134 in memory. For example, the control devices 120-124 maystore an intensity and/or a color temperature of the respective lightingload 130-134 in memory.

The load control devices 120, 122, 124 and the lighting loads 130-134may be powered by power generated by an electric utility (e.g., AC mainspower). For example, load control device 122 and 124 may be powered by(i.e., receive power from) a utility power source 102. However, theutility power 102 may occasionally experience power outages. Therefore,the space or building in which the load control system 100 is installedmay also have a backup power source 106. The backup power source 106 maybe configured to provide power to one or more of the load controldevices 120-124 and lighting loads 130-134 in the event of a poweroutage. For example, building codes may require commercial buildings topower one or more of the lighting loads in the event of a power outageof the utility power source 102 to maintain a minimum light level in thespace during the power outage. Some example building codes which outlinethe requirements for emergency lighting and power are the National FireProtection Association (NFPA) 101 Life Safety Code, NFPA 1 Fire Code,International Building Code IBC, International Fire Code (IBC), and NFPA70: National Electric Code (NEC).

The lighting loads that are configured to be powered by the backup powersource during a power outage of the utility power source 102 may bereferred to as “emergency” lighting loads. For example, the lightingload 130 may be an emergency lighting load. The load control device 120which controls power to the emergency lighting load 130 may be connectedto a transfer switch 110, e.g., an automatic transfer switch (ATS). Thetransfer switch 110 may normally provide power to the load controldevice 120 (and therefore the lighting load 130) from the utility powersource 102. When a power outage occurs and the utility power 102 is nolonger able to power the load control device 120 and the lighting load130, the transfer switch 110 may changeover to providing power from thebackup power source 106. In this way, the emergency lighting load 130may remain illuminated to light a portion of the area in which the loadcontrol system 100 is installed, even when lighting loads 132 and 134have lost power due to the utility power outage. The backup power source106, which provides power to the emergency lighting loads, may be agenerator, a battery bank, one or more solar cells, etc.

When the utility power 102 experiences a power outage, the lightingloads 132, 134, the control devices 122, 124, and the system controller140 may all lose power. Additionally, the control device 120 and thelighting load 130 may also lose power for a brief duration of time(“power blip”) as the transfer switch 110 changes over from the utilitypower source 102 to the backup power 106. For example, the briefduration of time of a power blip may be greater than 250 millisecondsand less than or equal to 10 seconds. The control device 120 may rely onthe brief power dropout to sense that a power outage has occurred and toenter an emergency mode. For example, the power dropout may cause thecontrol device 120 to undergo a power cycle. Upon powerup, the controldevice 120 may startup in emergency mode. For example, the controldevice 120 may experience a power cycle or a power reset in response tothe power blip when the transfer switch 110 changes power from theutility power source 102 to the backup power source 106.

The emergency mode may include presets of a specified light level and/orcolor temperature. For example, prior to entering the emergency mode,the lighting load 130 may be turned off if the area is unoccupied.However, if the control device 120 senses a power outage (i.e.,experiences a power reset), the control device 120 may enter thepredefined emergency mode. In the emergency mode, the control device 120may cause the lighting load to turn on to 75% intensity, for example.One will understand that this intensity is provided as an example, andthat other light level (and/or changes in color temperature) presets arepossible. For example, the emergency light level may be 100% lightintensity.

While the control device 120 is in the emergency mode, the controldevice 120 may transmit an emergency mode message to one or more devicesin the load control system. The emergency mode message may betransmitted via a wired or wireless communication. Further, the controldevice 120 may repeatedly transmit the emergency mode message, forexample, transmit the message a plurality of times. For example, theload control device 120 may transmit an emergency mode message once perminute. The control device 120 may remain in emergency mode untilreceiving instructions from the load control system (i.e., via thesystem controller 140) to exit the emergency mode. The emergency modemessage may be transmitted at irregular intervals. For example,transmitting at irregular intervals may reduce the likelihood of twoload control devices transmitting at the same time (which may cause amessage collision), thereby reducing the risk that the message may belost if another device is transmitting a second message at the sametime. However, one will understand that the emergency mode message mayalternatively be transmitted periodically, that is, at regularintervals.

As described, the system controller 140 may lose power when the utilitypower 102 undergoes a power outage. When the utility power turns backon, the system controller 140, the load control devices 122, 124, andthe lighting loads 132, 134 may regain power. Upon regaining power, thesystem controller 140 may receive the emergency mode message from thecontrol device 120, which may still be in emergency mode. In response tothe system controller 140 receiving the emergency mode message, thesystem controller may transmit (i.e., broadcast) a command to thedevices in the load control system 100 (e.g., the control device 120).The command may instruct the control devices that the load controlsystem 100 is no longer in emergency mode. In response to the commandtransmitted by the system controller 140, the control device 120 mayexit emergency mode. Upon exiting the emergency mode, the control device120 may return to a last known state which may be recalled from thepower failure memory. For example, the control device 120 may recallfrom memory the stored values of intensity and/or color temperature thatwere previously used to control the lighting load 130 before theemergency mode was enabled. Alternatively, the control device 120 maydetermine whether the area is occupied (i.e., based on receiving anoccupancy command from one or more occupancy sensors 112). If the areais occupied, the control device 120 may turn on power to the load 130.If the area is not occupied, the control device 120 may turn off thelighting load 130.

FIG. 2 is an example process 200 which may be executed by a controlcircuit of a control device which controls an emergency lighting load,such as control device 120 of FIG. 1. The process may start at 202. At204, the control device may detect a power blip indicating that normalutility power may have been lost. For example, the power blip mayindicate that utility power source 102 has lost power and that thetransfer switch 110 has changed over to the emergency or backup powersource 106 to power the control device 120. Or, the power blip mayindicate that a momentary loss of utility power has occurred and beenrestored, for example, a short disruption of power.

In response to detecting the power blip, at step 206, the control devicemay enter the emergency mode by recalling emergency mode settings frommemory. For example, an emergency mode setting may be a light intensityof 75%. At step 210, the control device may control the respectivelighting loads according to the emergency mode settings (i.e., thecontrol device may enter emergency mode). At step 212, the controldevice may transmit an emergency mode message indicating that thecontrol device has entered emergency mode.

At step 216, the load control device may determine whether a command toexit emergency mode has been received. If the control device determinesthat a command to exit emergency mode has not been received, the controldevice may continue to periodically transmit the emergency mode messageat step 212. If the control device has received a command to exit theemergency mode at step 216, the control device may then exit theemergency mode at step 220, thereby resetting the light level of therespective emergency lighting load to the last known state, i.e., basedon recalling the light level (and/or color temperature) from powerfailure memory, as previously described. For example, if the emergencylighting load was in an off state when the power outage occurred, andthe emergency lighting load was subsequently turned on in emergencymode, the control device may return the emergency lighting load to theoff state when exiting the emergency mode. The process may end at step228.

One will understand that resetting the lighting load to the last knownstate when exiting emergency mode may further be dependent upon anoccupancy condition of the room. That is, the emergency load controldevice may set the intensity level and/or color temperature of thelighting load based on an occupancy state of the room in which thelighting load is installed. The emergency load control device mayreceive occupancy information from one or more occupancy sensors 112,and/or from one or more system controllers 140, to determine occupancyconditions.

For example, if the emergency lighting load 130 is installed in a roomthat was not occupied when the power outage occurred, but the room isoccupied when power returns, the last known state during normal power ofthe emergency lighting load 130 may be an off state (because the roomwas not occupied when the normal power was last on). When power is lost,the emergency lighting control device 120 may turn on the emergencylighting load 130 due to the power outage. The room may become occupiedbefore normal power is available. However, because the room is occupiedwhen power returns, it may be desirable that the emergency lightingcontrol device 120 maintain the emergency lighting load 130 in an onstate, and not return to the last known state (i.e., the off state) whennormal power resumes. For example, the emergency lighting control device120 may be configured to receive occupancy commands from the occupancysensor 112 and/or the system controller 140, and to store the occupancycommands in memory. Upon returning to normal power (e.g., the utilitypower source 102), the emergency lighting control device 120 mayretrieve the occupancy command from memory and based on the lastreceived occupancy command, the emergency lighting control device 120may determine whether the room is currently occupied. Based on thedetermination, the emergency lighting control device 120 may adjust thelight level of the lighting load 130. For example, if the emergencylighting control device 120 determines that the room is occupied, theemergency load control device 120 may maintain the load in an on state.However, if the emergency load control device 120 determines that theroom is not occupied, the emergency load control device 120 may turn offthe connected lighting load 130 when normal power is received.Alternatively, the emergency lighting control device 120 may receiveoccupancy commands during a power outage while the emergency lightingcontrol device 120 is powered by a backup power source 106. For example,the occupancy sensor 112 may be battery-powered, and may not bedependent upon the utility power source. Or, the control device 120 maycontrol the electrical load 130 based on message(s) received from theoccupancy sensor 112 after power has been restored when the controldevice 120 exits the emergency mode.

The occupancy commands received by the emergency load control device 120may be directly transmitted by one or more occupancy sensors 112.Alternatively, the system controller 140 may receive the occupancycommand(s) from one or more occupancy sensors 112 and may transmit theoccupancy command(s) to the respective emergency load control devicesfor that area in which the occupancy sensor(s) are located.Alternatively, the emergency load control device may have an integratedoccupancy sensor. For example, the load control device 120 may have anoccupancy sensor that is physically located on the fixture 130.

FIG. 3 is an example process 300 which may be executed by a controlcircuit of a system controller, such as the system controller 140, afterpower has been restored from a power outage. The process 300 may startat step 302. At step 304, the system controller may receive an emergencymode message. The emergency mode message may be from one or multipleemergency load control devices which may be operating in an emergencymode. Because the system controller is powered by utility power, thesystem controller may determine based on receiving the emergency modemessage that power has been restored (i.e., the system controller canonly receive the emergency mode message when utility power has beenrestored). At step 306, the system controller may transmit a command toexit emergency mode. The command may be transmitted wirelessly or via awired connection to the one or multiple emergency load control devices.The process 300 may end at step 316.

A system may operate wherein the emergency mode devices enter and remainin an emergency mode until receiving a command to exit emergency mode,i.e., the emergency mode control devices do not transmit messagesindicating that the control device is in emergency mode. However,different startup times between the system controller and other loadcontrol devices and/or control devices on separate circuits may lead toone or more control devices remaining in the emergency mode after powerhas been restored (i.e., instead of exiting the emergency mode andreturning to normal operation). An advantage that the process 300provides is that the process 300 detailed here may allow the controldevices to exit the emergency mode when power is restored, which mayapply not only for accidental power outages, but also for power outagesdue to routine maintenance. For example, if both the backup power andthe utility power are temporarily turned off for electrical circuitmaintenance, the emergency load control devices may startup in emergencymode when power is restored. Different load control devices (or loadcontrol devices on separate circuits) may take different amounts of timeto startup and begin transmitting emergency mode messages. The advantagethat the process 300 provides by allowing a command to exit emergencymode to be transmitted based on the system controller receiving anemergency mode message is that emergency load control devices withdifferent startup times may not miss the command to exit emergency modetransmitted by the system controller.

One disadvantage of the load control system 100 described in FIG. 1 isthat the emergency load control devices may not be able to detect whento enter emergency mode if the emergency load control devices arepowered by uninterruptible power supplies (i.e., if there is no powerblip when power changes from the utility power to the backup powersupply). FIG. 4 is an example load control system 400 that may besimilar to the load control system 100 of FIG. 1. For example, the loadcontrol system 400 may have a utility power source 402 and a backuppower source 406. The load control system may also include one or moreoccupancy sensor(s) 412. The control devices 422, 424 may be connectedto utility power 402 and may control one or more connected lightingloads 432, 434. The load control system 400 may also include a systemcontroller 440 and an emergency load control device 420 with a connectedemergency lighting load 430. The emergency load control device 420 andthe system controller 440 may be connected to, i.e., receive power from,the backup power source 406. The backup power source 406 may be anuninterruptible backup power source, for example, a battery backup powersource.

The load control devices 420, 422, and 424 may receive power from theutility power source 402 during normal operation. For example, the loadcontrol devices 422, 424 may be directly powered by the utility powersource. The emergency load control device 420 may be powered by theuninterruptible backup power source, which may also receive power fromthe utility power source 402. In the event of a power outage of thenormal or primary utility power source 402, the uninterruptible backuppower source 406 may changeover to provide power from the backup powersource 406 (e.g., the battery backup).

In the configuration shown, the system controller 440 may also beconnected to the uninterruptible backup power source 406. That is, thesystem controller 440 may remain powered in the event of a power outageof the utility power 402. Therefore, to detect a power outage, the loadcontrol system 400 may further include a detector 450. The detector 450may receive power from the utility power 402 and may be configured tosense a loss in power of the utility power. For example, the detector450 may sense that a power outage has occurred and the utility power 402is no longer present. The detector 450 may transmit one or more messagesto the system controller 440 based on detecting a power outage. Thedetector 450 may transmit messages via a wired or wireless connection.For example, the detector 450 may communicate via radio frequency (RF)signals 460 to the system controller 440. The detector 450 maycommunicate using any protocol, including, but not limited to: ZigBee,Bluetooth, Thread, or a proprietary protocol such as ClearConnect, etc.Alternatively or additionally, the detector 450 may communicate to thesystem controller 440 by changing a state of a relay or a contactclosure output.

The system controller 440 may receive the message from the detector 450indicating that a power outage has occurred. Upon receiving the message,the system controller may send a command to the load control devices ofthe system 400 to enter emergency mode. The devices of the system 400which are still powered by the backup power source 406 (i.e., controldevice 420) may then set their respective loads to the emergency modelevels in response to receiving the emergency mode command.

One will understand that the power loss sense of the detector 450 mayalternatively be added into the system controller 440. For example, thedetector and/or the system controller comprising a detector may bepowered via the utility power 402. The detector and/or system controllermay contain a transient power supply (such as a capacitor), or a secondpower supply source, such as a battery, for example, which may allow thedetector and/or the system controller to remain powered for at least aminimum amount of time required to send the emergency mode command tothe emergency devices after a power outage has occurred.

The control device 420 may exit the emergency mode in any of severalways. According to a first example, similar to the example describedwith respect to FIG. 1, when the control device 420 is in the emergencymode, the control device 420 may transmit a message (i.e., repeatedlytransmit a plurality of messages) indicating that the control device 420is in the emergency mode. The detector 450 may transmit a message to thesystem controller 440 when power has been restored to the utility powersource 402. The system controller may then transmit a message to theload control device 420 to exit the emergency mode in response toreceiving the message from the detector that power is restored andreceiving the message from the control device 420.

Alternatively, the control device 420 may not transmit the emergencymode message, but may rely on the detector to communicate with thesystem controller 440 , with the system controller then instructing thecontrol device 420 to enter and exit the emergency mode.

An additional variation of the load control system setup is shown inFIG. 5, which depicts a load control system 500 having multi-phasepower. Similar to FIG. 4, the load control system 500 may have a utilitypower source 502 and a detector 550 for monitoring power loss of theutility power source 502. The detector 550 may wirelessly communicatewith a system controller 540 via wireless signals 560, similar to thatpreviously described for FIG. 4. (One will recognize wired communicationvariations may alternatively be implemented). Similar to FIG. 1, theload control system 500 may also contain a backup power source 506, andmay further include a transfer switch 550 between the utility andemergency power supplies. For example, the transfer switch 550 may be anautomatic transfer switch (ATS). Alternatively, and/or additionally, thebackup power source 506 may include a battery backup, as described forFIG. 4. The load control system 500 may further contain one or moreoccupancy sensor(s) 512, similar to occupancy sensor 412 of FIG. 4.

In this example, the load control system 500 may have multi-phase power.For example, the load control system 500 may have three-phase power, asindicated by the solid and dashed lines showing phases A, B, and C. Thedevices of the load control system 500 may be wired to different phasesof power. For example, although each load control device 520, 522, and524 are wired to the transfer switch 550, each of the load controldevices is shown as wired to a different phase of power. For example,control device 524 is wired to Phase A, control device 522 is wired toPhase B, and control device 520 is wired to Phase C. One will understandthat groups of devices may be wired to different power phases, that is,additional devices may be wired to any of the respective power phases A,B, or C. For example, multiple load control devices may be wired to thesame phase of power. The load control devices 520, 522, and 524 maycontrol respective electrical loads, shown as lighting loads 530, 532,and 534.

Although the load control system 500 is shown as having a backup powersource 506 with three phases of power, one will recognize that eachpower phase may be either a normal power supply with an emergency (i.e.,backup) power supply, or, one or more power phases may only be poweredby a normal power supply (i.e., utility power). In this example, thephases of power which are connected to the backup power supply 506 maybe operable to enter an emergency mode. For example, if Phase B is onlyconnected to the utility power 502, and not the backup power supply 506,the load control device 522 which is connected to Phase B may lose powerduring a power outage of the utility power 502 and may not enteremergency mode.

When a power outage occurs on one or more power phases A, B, and/or C,the transfer switch 550 may changeover power to the backup power source506, similarly as has been described for the backup power source 106 ofFIG. 1. For example, the transfer switch may be an automatic transferswitch (ATS). The changeover of power by the transfer switch 550 fromthe utility power source 502 to the backup power source 506 may create amomentary loss of power in one or more of the load control devices520-524 (i.e., a power blip). The power blip may cause one or more ofthe load control devices 520-524 to experience a power on reset. Inresponse to the power on reset, the load control device(s) may enteremergency mode. For example, phase C may experience a power outage. Theload control device 520, which receives power from Phase C, as shown,may experience a power on reset as the transfer switch 550 changes overfrom the utility power source 502 to the backup power source 506. Theload control device 520 may detect that a power blip has occurred (i.e.,may detect a power on reset). In response to the power blip detection,the load control device 520 may enter emergency mode, and may set thelighting load 530 to an emergency mode level. The load control device520 may transmit a message indicating that the load control device is inemergency mode.

The detector 550 may be configured to detect a power outage of any orall of the phases A, B, and C of the utility power 502. The detector 550may transmit a message to the system controller when one or more phasesof power has been lost (i.e., a power outage has occurred). For example,the detector 550 may trigger a contact closure output or change thestate of a relay to alert the system controller 540 that a power outagehas occurred.

Alternatively and/or additionally, the detector 550 may wirelesslytransmit a message to the system controller 540 to indicate a poweroutage has occurred. The system controller 540 may receive the emergencymode message from the load control device 520. The system controller 540may further receive a power outage message from the detector 550indicating that power has been lost on one or more phases of the utilitypower source. After receiving the power outage message from the detector550, the system controller may transmit a command to the devices of theload control system 500 (i.e., control devices 520, 522, and 524) tocause the load control devices to enter emergency mode. The load controldevices 522 and 524 may enter emergency mode in response to receivingthe command by the system controller 540. The control device 520 mayalso enter emergency mode in response to the command from the systemcontroller 540, or the control device 520 may have previously enteredthe emergency mode based on detecting the power outage on Phase C, aspreviously described. When entering emergency mode, the load controldevices 520, 522, and 524 may set their respective loads (e.g., lightingloads) 530, 532, 534, to their emergency mode levels.

When power is restored, the detector 550 may transmit a message to thesystem controller 540 that power has been restored. In response to themessage that power has been restored, the system controller may transmita command to one or more devices of the load control system 500 toinstruct the devices to return to normal operation. For example, theload control device 520 may be in an emergency mode. In response toreceiving a command to return to normal operation (i.e., exit emergencymode), the device may exit emergency mode and restore the connectedlighting load 530 to a previous light intensity and/or colortemperature, as previously described. In this example, the systemcontroller may be connected to normal or emergency power. For example,if no backup power is connected to phase C, the system controller may bepowered solely by the normal utility power. When the utility powerexperiences a power outage, the system controller may rely on atransient or secondary power supply to remain powered at least untilsending out the command to the load control devices to enter emergencymode. For example, the system controller may be powered by a capacitor,solar cell, backup battery, etc.

FIG. 6 is an example method 600 which may be executed by the systemcontroller during a power outage, according to the system diagram ofFIG. 5. The method may start at 602. At 604, the system controller maydetect a temporary power outage (i.e., a power blip). In a firstexample, the system controller may be configured to detect the momentaryloss of power as the system changes over from normal power to emergencypower. In a second example, the system controller may only be connectedto normal utility power and may detect a power outage as previouslydescribed. In a third example, the system controller may receive acommunication from a detector, such as the detector 550, that a powerblip or a power outage has occurred. The detector may be connected onlyto normal utility power, or the detector may be connected tonormal/emergency power, as previously described. At step 606, the systemcontroller may send a command to the devices of the load control systemto go into emergency mode.

When normal power returns, the system controller may detect that powerhas returned at step 610. The system controller may detect the return ofpower in any of several ways. For example, the system controller may beattached to a phase of power that does not have a backup power, and thesystem controller may sense that power has been applied to the powerterminals of the system controller. In another example, the detector maycommunicate to the system controller that power has been restored. Thedetector may be connected to one or several phases of power. Forexample, the detector may be connected to all three phases of power andmay communicate to the system controller when any or all of the phaseshave experienced a power outage.

In response to detecting that power has returned, the system controllermay transmit a command to all devices to return the load control devicesto normal operation at 616. For example, the devices which were poweredby the backup power source and operating in emergency mode may return tonormal operation, as previously described. At 628, the method may end.

FIG. 7 is an example block diagram of a load control device 700, whichmay be responsive to entering an emergency mode, such as such as device120 of FIG. 1, device 420 of FIG. 4, or any of devices 520, 522, and 524of FIG. 5.

The control device 700 may be powered by a power source 702. The powersource 702 may be any suitable alternating current (AC) or directcurrent (DC) power source. For example, the power source 702 may be anAC line voltage. Alternatively, the power source 702 may be a DC powersource, such as a 12- or 48-volt supply provided by low voltage wires,Power over Ethernet (PoE), battery, solar cell, etc.

The control device 700 may have a hot terminal H for receiving powerfrom an AC line voltage 702. The control device 700 may have a dimmedhot or switched hot terminal DH for providing power to a load 707. Theload 707 may be a lighting load, such as an LED, a compact fluorescentlamp (CFL), incandescent lamp, halogen lamp, etc. For example, thelighting load may be any of load 130 of FIG. 1, 430 of FIG. 2, or 530,532 or 534 of FIG. 5. The control device 700 may further have a neutralterminal N connected to a neutral connection of the power source 702.

The control device 700 may have a zero-cross detector 718 and a loadcontrol circuit 710. The zero-cross detector 718 and the load controlcircuit 710 may both be electrically connected to the hot terminal H andthe control circuit 717. The zero-cross detector may monitor the linevoltage from the hot terminal H to detect when the line voltage reachesa minimum. When the line voltage reaches a minimum, the zero-crossdetector may provide a zero-cross timing signal to the control circuit717. The control circuit may control the load control circuit 710 basedon the zero-cross timing signal provided by the zero-cross detector 718.For example, the control circuit 717 may control the load controlcircuit 710 to provide a dimmed hot signal on terminal DH, where thedimmed hot signal may use phase angle dimming. The firing time of theload control circuit to provide the desired phase angle of the dimmedhot signal may be based on the zero-cross signal from the zero-crossdetector 718. The load control circuit may be a controllably conductivedevice, such as a triac, silicon-controlled rectifier (SCR),field-effect transistor (FET), or the like.

The control device 700 may contain at least one power supply 722 whichsupplies a voltage V_(CC) for powering the electronic circuitry of thecontrol device. For example, the control device 700 may have a controlcircuit 717. The control circuit 717 may be powered by the voltageV_(CC) provided by the power supply 722. The control circuit 717 mayinclude one or more of a processor(s) (e.g., a microprocessor(s)), amicrocontroller(s), a programmable logic device(s) (PLD), a fieldprogrammable gate array(s) (FPGA), an application specific integratedcircuit(s) (ASIC), or any suitable controller or processing device orcombination thereof.

The control device 700 may further include one or more actuators 716 forcontrolling the electrical load 707 and/or for programming orcommissioning the load control device. For example, the actuator(s) 716may be used to associate the control device 700 with one or more devicesin the system during commissioning of the system. For example, a usermay press the actuator(s) 716 to associate the control device 700 with asystem controller, or with another control device, or sensor, etc. Theactuator(s) 716 may be electrically connected to the control circuit717. The actuators(s) 716 may include one or more actuators (on/off,dim, etc.). For example, the control circuit 717 may control the loadcontrol circuit 710 based on user input received from the user interface716. For example, a user may actuate an on or off switch on the userinterface 716 of the control device 700, and the control device 700 maycontrol the load 707 on or off in response to receiving the user inputat the user interface 716. Additionally, or alternatively, the userinput may comprise dimming actuators for dimming the load 707 up anddown.

The control device 700 may contain one or more light emitting diodes(LEDs) 772. LEDs 772 may be connected to the control circuit 717. TheLEDs 772 may be used to communicate to a user by turning the LEDs on oroff, and/or changing the color of the LEDs. For example, the LEDs 772may change state when the control device 700 is in emergency mode. Forexample, the LEDs 772 may blink on and off repeatedly, or with aspecific blink sequence, to indicate to a user that the control device700 is in emergency mode. According to one example of a specific blinksequence, the LEDs 772 may turn on for a first period of 2000milliseconds (ms), off for 200 ms, on for 200 ms, and off for 200 ms,after which the specific blink sequence may be repeated. Alternatively,the LEDs 772 may change color, for example, may turn from green to red,etc., to indicate to a user that the control device 700 is in emergencymode.

The control device 700 may contain one or more communication circuits727 which are operably connected to the control circuit 717. Thecommunication circuit 727 may be a wireless or a wired communicationcircuit and may receive wireless or wired signals from other devices inthe load control system, such as the system controller. The signalsreceived by the communication circuit 727 may contain load controlcommands. The control circuit may receive the signals from thecommunication circuit 727 and may control the load control circuit 710based on the received signals. The communication circuit 727 may be awireless communication circuit. The communication protocol may includeone or more of the following: Wi-Fi, ZigBee, Bluetooth, Thread, or aproprietary protocol such as a ClearConnect, etc. Alternatively, thecommunication circuit 727 may be a wired communication circuit, forexample, a USB-C, Ethernet or Cat5, Serial cable, or any other type ofcommunication wiring. For example, the load control device 700 maycommunicate to the system controller via a wired protocol, such as aDALI or ECOSYSTEM communication protocol.

The control device 700 may have one or more memory modules (“memory”)720 (including volatile and/or non-volatile memory modules) that may benon-removable memory modules and/or removable memory modules. Memory 720may be communicatively coupled to the control circuit 717. Non-removablememory 720 may include random-access memory (RAM), read-only memory(ROM), a hard disk, or any other type of non-removable memory storage.Removable memory 720 may include a subscriber identity module (SIM)card, a memory stick, a memory card, or any other type of removablememory. The memory 720 may have instructions, such as software basedinstructions, stored thereon that when executed by the control circuit717 configure the control circuit to provide functionality as describedherein.

FIG. 8 is an example block diagram of a system controller 800, such assuch as system controller 140 of FIG. 1, system controller 440 of FIG.4, or system controller 540 of FIG. 5. The system controller 800 mayhave a hot terminal H and a neutral terminal N for receiving power froman AC line voltage 802.

The system controller 800 may contain at least one power supply 822which may supply a voltage V_(CC) for powering the electronic circuitryof the system controller. The system controller 800 may have a controlcircuit 818. The control circuit may be powered by the voltage V_(CC)provided by the power supply 822. The control circuit may include one ormore of a processor(s) (e.g., a microprocessor(s)), amicrocontroller(s), a programmable logic device(s) (PLD), a fieldprogrammable gate array(s) (FPGA), an application specific integratedcircuit(s) (ASIC), or any suitable controller or processing device orcombination thereof.

The system controller 800 may contain one or more communication circuits828 which are operably connected to the control circuit 818. Thecommunication circuit 828 may be a wireless or a wired communicationcircuit and may transmit wireless or wired signals to other devices inthe load control system, such as load control devices. The signalstransmitted by the communication circuit 828 may contain load controlcommands. The control circuit may also receive signals from a detectorand may transmit messages, such as emergency mode messages, based on thereceived signals.

The communication circuit 828 may be a wireless communication circuit.The communication protocol may include one or more of the following:Wi-Fi, ZigBee, Bluetooth, Thread, or a proprietary protocol such as aClearConnect, etc. Alternatively, the communication circuit 828 may be awired communication circuit, for example, a USB-C, Ethernet or Cat5,Serial cable, or any other type of communication wiring. For example,the system controller 800 may communicate to one or more load controldevices via a wired protocol, such as a DALI or ECOSYSTEM communicationprotocol.

The system controller 800 may have one or more memory modules (“memory”)820 (including volatile and/or non-volatile memory modules) that may benon-removable memory modules and/or removable memory modules. Memory 820may be communicatively coupled to the control circuit 818. Non-removablememory 820 may include random-access memory (RAM), read-only memory(ROM), a hard disk, or any other type of non-removable memory storage.Removable memory 820 may include a subscriber identity module (SIM)card, a memory stick, a memory card, or any other type of removablememory.

The system controller 800 may also contain one or more LEDs 832. TheLEDs may be used to communicate a system status to the user.

The system controller 800 may further include a sense circuit 840. Thesense circuit may be operable to detect a power outage. For example, thesense circuit 840 may detect a momentary power loss or power blip as theinput power 802 changes from a normal utility power source to a backuppower source, such as a generator.

Although features and elements are described herein in particularcombinations, each feature or element can be used alone or in anycombination with the other features and elements. The methods describedherein may be implemented in a computer program, software, or firmwareincorporated in a computer-readable medium for execution by a computeror processor. Examples of computer-readable media include electronicsignals (transmitted over wired or wireless connections) andnon-transitory/tangible computer-readable storage media. Examples ofnon-transitory/tangible computer-readable storage media include, but arenot limited to, a read only memory (ROM), a random-access memory (RAM),removable disks, and optical media such as CD-ROM disks, and digitalversatile disks (DVDs).

What is claimed is:
 1. An electrical load control device, comprising:communications interface circuitry; memory circuitry; and controlcircuitry communicatively coupled to the memory circuitry and thecommunications interface circuitry, the control circuitry to: determinewhether an interruption in utility power has occurred and responsive tothe determination that an interruption in utility power has occurred:save, in the memory circuitry, data representative of an originaloperating mode of one or more operatively coupled electrical loads;generate an output to cause the one or more operatively coupledelectrical loads to transition to an emergency operating mode;communicate, via the communications interface circuitry, a first messageto a system controller, the first message including informationindicative of the transition of the one or more operatively coupledelectrical loads to the emergency operating mode; responsive to receiptof a message from the system controller to exit the emergency operatingmode, determine if an operating mode control signal from the systemcontroller is present; responsive to the presence of the operating modecontrol signal, cause the one or more operatively coupled electricalloads to transition to an operating mode associated with the operatingmode control signal; and responsive to the absence of the operating modecontrol signal, retrieve the saved data representative of the originaloperating mode and cause the one or more operatively coupled electricalloads to transition to the original operating mode.
 2. The load controldevice of claim 1 wherein to determine if the operating mode controlsignal from the system controller is present, the control circuitry tofurther: determine if an occupancy control signal from the systemcontroller is present and, responsive to the presence of the occupancycontrol signal, cause the one or more operatively coupled electricalloads to transition to the operating mode associated with the occupancycontrol signal.
 3. The load control device of claim 1 wherein todetermine if the operating mode control signal from the systemcontroller is present, the control circuitry to further: determine if anambient light control signal from the system controller is present and,responsive to the presence of the ambient light control signal, causethe one or more operatively coupled electrical loads to transition tothe operating mode associated with the ambient light control signal. 4.The load control device of claim 1 wherein to communicate the firstmessage to the system controller, the control circuitry to further:communicate the first message to the system controller on a periodicbasis while the one or more operatively coupled electrical loads remainin the emergency operating mode.
 5. The load control device of claim 1wherein to communicate the first message to the system controller, thecontrol circuitry to further: communicate the first message to thesystem controller on an irregular basis while the one or moreoperatively coupled electrical loads remain in the emergency operatingmode.
 6. The load control device of claim 1 wherein to generate theoutput to cause the one or more operatively coupled electrical loads totransition to the emergency operating mode, the control circuitry tofurther: generate an output to cause one or more operatively coupledlighting loads to transition at least one of: an output luminousintensity or an output color temperature to an emergency operating mode7. An electrical load control method, comprising: determining, byelectrical load control circuitry, whether an interruption in utilitypower has occurred and responsive to the determination that aninterruption in utility power has occurred: saving, by the electricalload control circuitry in communicatively coupled memory circuitry, datarepresentative of an original operating mode of one or more operativelycoupled electrical loads; generating by the electrical load controlcircuitry, an output to cause the one or more operatively coupledelectrical loads to transition to an emergency operating mode;communicating, by the electrical load control circuitry viacommunicatively coupled communications interface circuitry, a firstmessage to a system controller, the first message including informationindicative of the transition of the one or more operatively coupledelectrical loads to the emergency operating mode; responsive to receiptof a message from the system controller to exit the emergency operatingmode, determining by the electrical load control circuitry, if anoperating mode control signal from the system controller is present;responsive to the presence of the operating mode control signal, causingthe one or more operatively coupled electrical loads to transition to anoperating mode associated with the operating mode control signal; andresponsive to the absence of the operating mode control signal,retrieving, by the electrical load control circuitry from the memorycircuitry, the saved data representative of the original operating mode;and causing the one or more operatively coupled electrical loads totransition to the original operating mode.
 8. The method of claim 7wherein determining if the operating mode control signal from the systemcontroller is present further comprises: determining, by the electricalload control circuitry, if an occupancy control signal from the systemcontroller is present and, responsive to the presence of the occupancycontrol signal, causing the one or more operatively coupled electricalloads to transition to the operating mode associated with the occupancycontrol signal.
 9. The method of claim 7 wherein determining if theoperating mode control signal from the system controller is presentfurther comprises: determining, by the electrical load controlcircuitry, if an ambient light control signal from the system controlleris present and, responsive to the presence of the ambient light controlsignal, causing the one or more operatively coupled electrical loads totransition to the operating mode associated with the ambient lightcontrol signal.
 10. The method of claim 7 wherein communicating thefirst message to the system controller further comprises: communicating,by the electrical load control circuitry, the first message to thesystem controller on a periodic basis while the one or more operativelycoupled electrical loads remain in the emergency operating mode.
 11. Themethod of claim 7 wherein communicating the first message to the systemcontroller further comprises: communicating, by the electrical loadcontrol circuitry, the first message to the system controller on anirregular basis while the one or more operatively coupled electricalloads remain in the emergency operating mode.
 12. The method of claim 7wherein generating the output to cause the one or more operativelycoupled electrical loads to transition to the emergency operating mode,the control circuitry to further: generating, by the electrical loadcontrol circuitry, an output to cause one or more operatively coupledlighting loads to transition at least one of: an output luminousintensity or an output color temperature to an emergency operating mode13. A non-transitory, machine-readable, storage device that includesinstructions that when executed by electrical load control circuitry,causes the control circuitry to: determine whether an interruption inutility power has occurred and responsive to the determination that aninterruption in utility power has occurred: save, in communicativelycoupled memory circuitry, data representative of an original operatingmode of one or more operatively coupled electrical loads; generate anoutput to cause the one or more operatively coupled electrical loads totransition to an emergency operating mode; communicate, viacommunicatively coupled communications interface circuitry, a firstmessage to a system controller, the first message including informationindicative of the transition of the one or more operatively coupledelectrical loads to the emergency operating mode; responsive to receiptof a message from the system controller to exit the emergency operatingmode, determine if an operating mode control signal from the systemcontroller is present; responsive to the presence of the operating modecontrol signal, cause the one or more operatively coupled electricalloads to transition to an operating mode associated with the operatingmode control signal; and responsive to the absence of the operating modecontrol signal, retrieve the saved data representative of the originaloperating mode and cause the one or more operatively coupled electricalloads to transition to the original operating mode.
 14. Thenon-transitory, machine-readable, storage device of claim 13 wherein theinstructions that cause the electrical load control circuity todetermine if the operating mode control signal from the systemcontroller is present, cause the control circuitry to further: determineif an occupancy control signal from the system controller is presentand, responsive to the presence of the occupancy control signal, causethe one or more operatively coupled electrical loads to transition tothe operating mode associated with the occupancy control signal.
 15. Thenon-transitory, machine-readable, storage device of claim 13 wherein theinstructions that cause the electrical load control circuity todetermine if the operating mode control signal from the systemcontroller is present, cause the control circuitry to further: determineif an ambient light control signal from the system controller is presentand, responsive to the presence of the ambient light control signal,cause the one or more operatively coupled electrical loads to transitionto the operating mode associated with the ambient light control signal.16. The non-transitory, machine-readable, storage device of claim 13wherein the instructions that cause the electrical load control circuityto communicate the first message to the system controller, cause thecontrol circuitry to further: communicate the first message to thesystem controller on a periodic basis while the one or more operativelycoupled electrical loads remain in the emergency operating mode.
 17. Thenon-transitory, machine-readable, storage device of claim 13 wherein theinstructions that cause the electrical load control circuity tocommunicate the first message to the system controller, cause thecontrol circuitry to further: communicate the first message to thesystem controller on an irregular basis while the one or moreoperatively coupled electrical loads remain in the emergency operatingmode.
 18. The non-transitory, machine-readable, storage device of claim13 wherein the instructions that cause the electrical load controlcircuity to generate the output to cause the one or more operativelycoupled electrical loads to transition to the emergency operating mode,causeT the control circuitry to further: generate an output to cause oneor more operatively coupled lighting loads to transition at least oneof: an output luminous intensity or an output color temperature to anemergency operating mode